1. Field of the Invention
This invention relates to perimeter or border lighting and more particularly to perimeter or border lighting for curved surfaces using light emitting diodes as the light source.
2. Description of the Related Art
Perimeter or border lights (“perimeter lighting”) are commonly used on buildings to accentuate the structure, to draw customer attention to the building, and to provide safety lighting. Most conventional perimeter lights use neon bulbs for the light source. Some of the disadvantages of neon lighting is that neon bulbs have a relatively short life, are fragile and can consume a relatively large amount of power. Also, neon bulbs can experience difficulty with cold starting, which can lead to the bulb's failure.
Advancements in light emitting diode (“LED”) technology has resulted in devices that are brighter, more efficient and more reliable. LEDs are now being used in many different applications that were previously the realm of incandescent bulbs, some of which include displays, automobile taillights and traffic signals. As the efficiency of LEDs improve it is expected that they will be used in most lighting applications.
U.S. Pat. No. 4,439,818 to Scheib discloses a lighting strip that utilizes LEDs as the light source. The strip is flexible in three dimensions and is useful in forming characters and is capable of providing uniform illumination regardless of the characters selected for display. The strip comprises a flexible multi-layered pressure sensitive adhesive tape that has a plurality of triangle cutout sections on each side of the tape to allow the tape to bend. LEDs are connected in a series with a resister along the tape. One disadvantage of this strip is that it cannot be cut to match the different lengths of a particular feature to be illuminated, and still be connected in a series with other LED strips. Light from the LEDs is also not diffused so the tape does not give the appearance of neon light. This arrangement is also not durable enough to withstand the conditions for outdoor use because the flexible tape and its adhesive can easily deteriorate when continually exposed to the elements.
U.S. Pat. No. 5,559,681 to Duarte, discloses a flexible, self adhesive, light emissive material that can be cut into at least two pieces. The light emissive material includes a plurality of electrically coupled light emissive devices such as light emitting diodes. The material also includes electric conductors for conducting electric power from the source of electric power to each of the light emissive devices. While this lighting arrangement is cuttable to different lengths, the light it emits is not dispersed to appear as a neon light source. This arrangement is also not durable enough to withstand the conditions for outdoor use.
PCT International Application Number PCT/AU98/00602 discloses perimeter light that uses LEDs as its light source and includes a light tube structure in which multiple LEDs are arranged within an elongated translucent tube that diffuses or disperses the light from the LEDs. The perimeter light is used to highlight or decorate one or more features of a structure, such as a roof edge, window, door or corner between a wall or roof section.
One of the disadvantages of this perimeter light is that it cannot be cut to match the length of a building's structural features. Instead, it must be custom ordered or it is mounted without fully covering the structural feature. Also, the connectors between adjacent sections of lighting are bulky and result in a visible junction between the sections. The light's tube significantly attenuates the light emitted by its LEDs, significantly reducing the light's brightness. Further, the light does not include a mechanism for compensating for the expansion and contraction between adjacent lights. There is also no apparatus or method for providing perimeter lighting that can be bent to match a curved structural feature of a building.